// 导出页面为PDF格式
// https://blog.csdn.net/qq_27312237/article/details/113176503
import html2Canvas from 'html2canvas';
import JsPDF from 'jspdf';

/**
 * 导出dom为pdf
 */
function htmlToPdf(title : string, dom : HTMLElement) {
	console.log(dom)
	html2Canvas(dom, {
		allowTaint: true,
		scale: 2,
		useCORS: true,
	}).then(function (canvas) {
		const contentWidth = canvas.width
		const contentHeight = canvas.height
		const pageHeight = contentWidth / 592.28 * 841.89
		let leftHeight = contentHeight
		let position = 20
		const imgWidth = 595.28
		const imgHeight = 592.28 / contentWidth * contentHeight
		const pageData = canvas.toDataURL('image/jpeg', 1.0)
		const pdf = new JsPDF('p', 'pt', 'a4')
		if (leftHeight < pageHeight) {
			pdf.addImage(pageData, 'JPEG', 0, position, imgWidth, imgHeight)
		} else {
			while (leftHeight > 0) {
				pdf.addImage(pageData, 'JPEG', 0, position, imgWidth, imgHeight)
				leftHeight -= pageHeight
				position -= 841.89 + 20
				if (leftHeight > 0) {
					pdf.addPage();
				}
			}
		}
		pdf.save(title + '.pdf');
	})
}
/**
 * 导出dom为pdf,此方法有缺陷
 */
// https://www.cnblogs.com/jsonYoung/p/9806903.html
function myExportPdf(title : string, dom : HTMLElement) {
	var w = dom.offsetWidth;     // 获得该容器的宽
	var h = dom.offsetHeight;    // 获得该容器的高
	var offsetTop = dom.offsetTop;    // 获得该容器到文档顶部的距离
	var offsetLeft = dom.offsetLeft;    // 获得该容器到文档最左的距离
	var canvas = document.createElement("canvas");
	var abs = 0;
	var win_i = document.body.clientWidth;    // 获得当前可视窗口的宽度（不包含滚动条）
	var win_o = window.innerWidth;    // 获得当前窗口的宽度（包含滚动条）
	if (win_o > win_i) {
		abs = (win_o - win_i) / 2;    // 获得滚动条长度的一半
	}
	canvas.width = w * 2;    // 将画布宽&&高放大两倍
	canvas.height = h * 2;
	var context = <CanvasRenderingContext2D>canvas.getContext("2d");
	context.scale(2, 2);
	context.translate(-offsetLeft - abs, -offsetTop);
	// 这里默认横向没有滚动条的情况，因为offset.left(),有无滚动条的时候存在差值，因此
	// translate的时候，要把这个差值去掉
	html2Canvas(dom, {
		scale: 2,
		canvas: canvas,
		width: w,
		height: h
	}).then(function (canvas) {
		var contentWidth = canvas.width;
		var contentHeight = canvas.height;
		//一页pdf显示html页面生成的canvas高度;
		var pageHeight = contentWidth / 592.28 * 841.89;
		//未生成pdf的html页面高度
		var leftHeight = contentHeight;
		//页面偏移
		var position = 0;
		//a4纸的尺寸[595.28,841.89]，html页面生成的canvas在pdf中图片的宽高
		var imgWidth = 595.28;
		var imgHeight = 592.28 / contentWidth * contentHeight;

		var pageData = canvas.toDataURL('image/jpeg', 1.0);

		var pdf = new JsPDF('p', 'pt', 'a4');

		//有两个高度需要区分，一个是html页面的实际高度，和生成pdf的页面高度(841.89)
		//当内容未超过pdf一页显示的范围，无需分页
		if (leftHeight < pageHeight) {
			pdf.addImage(pageData, 'JPEG', 0, 0, imgWidth, imgHeight);
		} else {
			// 分页
			while (leftHeight > 0) {
				pdf.addImage(pageData, 'JPEG', 0, position, imgWidth, imgHeight)
				leftHeight -= pageHeight;
				position -= 841.89;
				//避免添加空白页
				if (leftHeight > 0) {
					pdf.addPage();
				}
			}
		}
		pdf.save(title);
	})
}
export default {
	htmlToPdf, myExportPdf
}